Vehicle front lamp

ABSTRACT

A vehicle front lamp includes a light source upper and lower first curved surfaces made of composite curved surfaces to reflect a light beam from a light source in the left direction and in the right direction, respectively, the upper and lower first curved surfaces being respectively mounted at higher and lower positions than the light source; and upper and lower second curved surfaces for reflecting a light beam reflected from the upper and lower first curved surfaces for making the light beam substantially parallel in the forward direction of the vehicle, the upper and lower second curved surfaces being mounted at the right and left of the light source. The composite curved surfaces of the upper first curved surface are slanted by an angle of 10 to 35 degrees so as to direct the reflected light beam downward; the composite curved surfaces of the lower first curved surface are slanted by an angle of 10 to 35 degrees so as to direct the reflected light beam upward. The upper and lower second curved surfaces are in contact relation with each other substantially along a line, and light shielding units are mounted at the right and left of the light source along the line defining the contact between the upper and lower second curved surfaces.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a front lamp for vehicles such asautomobiles.

2. Description of the Prior Art

Conventional vehicle front lamps are disclosed in, for example, JapaneseUtility Model Laid-open Publication Nos. 61-63702 and 61-71905 assignedto the same assignee as that of this invention. In Publication No.61-71905, there is disclosed a vehicle front lamp which comprises anupper first curved surface made of composite curved surfaces to reflecta light beam from a light source in the left direction and in the rightdirection, respectively, said upper first curved surface being mountedat the higher position than said light source; a lower first curvedsurface made of composite curved surfaces to reflect a light beam fromsaid light source in the left direction and in the right direction,respectively, said lower first curved surface being mounted at a lowerposition than said light source; an upper second curved surface forreflecting a light beam reflected from said upper first curved surfaceby making said light beam substantially parallel in the front direction,said upper second curved surface being mounted at the right and of saidlight source; and a lower second curved surface for reflecting a lightbeam reflected from said lower first curved surface by making said lightbeam substantially parallel in the front direction, said lower secondcurved surface being mounted at the right and left of said light source.

The above conventional lamp, however, has been found not to besatisfactory in that a light beam from a light source is reflected bythe second curved surfaces to generate stray light which when reflectedupward becomes dazzling light, to thereby pose a problem of difficultyin designing the light distribution of a front lamp. It has long beendesired to solve such a problem.

The above conventional lamp also has a disadvantage of insufficientilluminance and the like, in spite of its complicated structure.

SUMMARY OF THE INVENTION

It is therefore an object of the present invention to provide a vehiclefront lamp capable of eliminating dazzling light while attainingsufficient illuminance.

The above object is achieved by the vehicle front lamp according to thepresent invention, which comprises: an upper first curved surface madeof composite curved surfaces to reflect a light beam from a light sourcein the left direction and in the right direction, respectively, saidupper first curved surface being mounted at a higher position than saidlight source; a lower first curved surface made of composite curvedsurfaces to reflect a light beam from said light source in the leftdirection and in the right direction, respectively, said lower firstcurved surface being mounted at a lower position than said light source;an upper second curved surface for reflecting a light beam reflectedfrom said upper first curved surface by making said light beamsubstantially parallel in the front direction, said upper second curvedsurface being mounted at the right and left of said light source; and alower second curved surface for reflecting a light beam reflected fromsaid lower first curved surface by making said light beam substantiallyparallel in the front direction, said lower second curved surface beingmounted at the right and left of said light source; wherein saidcomposite curved surfaces of said upper first curved surface is slantedby an angle of 10 to 35 degrees so as to direct said reflected lightbeam downward; said composite curved surfaces of said lower first curvedsurface is slanted by an angle of 10 to 35 degrees so as to direct saidreflected light beam upward, said upper second curved surface and saidlower second curved surface are in contact relation with each other, andlight shielding units are mounted at the right and left of said lightsource along a line defining said contact between said upper and lowersecond curved surfaces. The light shielding units advantageouslyeliminate stray light. According to a preferred embodiment, a paraboloidof revolution is formed at the central front side portion of each ofsaid upper and lower first curved surfaces, said central front sideportion being an unavailable area relative to said second curvedsurfaces. According to a further embodiment, a third curved surface isformed at the surface of said light shielding units facing said lightsource, said third curved surface reflecting a light beam from saidlight source in the front direction. The above paraboloid of revolutionand the third curved surfaces provide sufficient illuminance.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view showing an embodiment of a vehicle frontlamp according to the present invention;

FIG. 2 is a cross section of FIG. 1 taken along line II--II in FIG. 1;

FIG. 3 is a front view of the embodiment shown in FIG. 1;

FIG. 4 is a diagram for explaining a light flux capture ratio;

FIG. 5 is a cross section showing the main part of a second embodimentof this invention;

FIG. 6 shows the light distribution of the second embodiment withoutusing a lens;

FIG. 7 is a perspective view showing the main part of a third embodimentof this invention;

FIG. 8 shows the light distribution of the third embodiment; and

FIG. 9 is a perspective view showing the main part of a fourthembodiment of this invention.

DETAILED DESCRIPTION

Throughout this specification, the terms "front", "back", "right"and"left" are intended to be used under the conditions that a front lamp ismounted on a vehicle. Namely, the front direction is the direction ofmoving a vehicle forward, the back direction is the direction of movingthe vehicle backward, the right direction and left direction are theright and left directions as viewed from a driver.

Referring now to FIGS. 1 to 3, the main part of a vehicle front lampaccording to the first embodiment of this invention is generallyindicated at 1. The vehicle front lamp 1 comprises of a light source 2,reflector 3, and lens 4 FIG. 2.

The structure of the reflector 3 will now be described in detail. Anupper first curved surface 31 is arranged at a higher position than thelight source 2, and a lower first curved surface 32 is arranged at alower position than the light source 2. The upper and lower first curvedsurfaces 31 and 32 reflect light from the light source 2 in the rightand left directions, respectively. The upper first curved surface 31 isa composite structure of an upper right curved surface 31a of aparaboloid of revolution and an upper left curved surface 31b of aparaboloid of revolution. Similarly, the lower first curved surface 32is a composite structure of a lower right curved surface 32a of aparaboloid of revolution and a lower left curved surface 32b of aparaboloid of revolution. At the right and left of the light source 2,there are arranged upper and lower second curved surfaces 33 and 34respectively corresponding to the upper and lower first curved surfaces31 and 32, for reflecting the reflected light from the first curvedsurfaces 31 and 32 forward by making the light substantially parallel.The upper and lower second curved surfaces 33 and 34 are made ofparabolic cylinder curved surfaces. The structure of the reflector 3described above is the same as conventional.

According to this invention, the upper right and left curved surfaces31a and 31b shaped in the form of parabolic cylinder surfaces areslanted by an angle of 10 to 35 degrees so as to direct the reflectedlight beam downward. Similarly, the lower right and left curved surfaces32a and 32b shaped in the form of parabolic cylinder surfaces areslanted by an angle of 10 to 35 degrees so as to direct the reflectedlight beam upward.

With the structure as described above, the reflected light from theupper and lower first curved surfaces 31 and 32 are aligned near analong a horizontal line passing through the light source 2. The upperand lower second curved surfaces 33 and 34 are disposed in contactrelation to each other along the horizontal line.

According to the present invention, in order to prevent light from thelight source 2 from being directly applied to the second curved surfaces33 and 34, there are further provided right and left light shieldingunits 35 and 36 at the right and left of the light source 2 along thehorizontal line, i.e., along the line defining the contact between theupper and lower second curved surfaces. The right and left lightshielding units 35 and 36 are respectively provided with right and leftthird curved surfaces 35a and 36a at positions facing the light source2, the third curved surfaces 35a and 36a being of a paraboloid ofrevolution with its focus set at the light source 2.

Reflected light beams from the first curved surfaces 31 and 32 propagatetoward the second curved surfaces 33 and 34. A fraction of the reflectedlight beams, however, is directly applied to the lens without beingapplied to the second curved surfaces 33 or 34, because of designrestrictions of the size of the second curved surfaces 33 and 34. Suchlight beams which are not applied to the second curved surfaces 33 or 34propagate slantwise relative to the horizontal plane by 10 to 35degrees, and generate dazzling light to thus hinder effective use oflight.

Such light beams which are not applied to the second curved surfaces 33or 34 are mainly generated at the center of the first curved surfaceswhich constitutes a light unavailable area. In view of this, accordingto the present invention, there are provided upper and lower fourthcurved surfaces 37 and 38 at the central front side portion of each ofthe first curved surfaces 31 and 32, the fourth curved surfaces being ofa paraboloid of revolution with a focus set at the light source 2.

The operation as well as the advantageous effects of the reflector 3constructed as above will now be described. The operation of similarelements is not described in duplicate, but the operation ofrepresentative elements only will be given.

Light beams from the light source 2 are reflected by the upper leftparabolic cylinder curved surface 31b of the upper first curved surface31. Since the upper left parabolic cylinder curved surface 31b isslanted downward, the effective reflection area increases as comparedwith a conventional one indicated by a broken line P in FIG. 4. Theincreased reflection area results in an increase of luminance of thefront lamp, because the luminance is determined by the light fluxcapture ratio of the reflector under the condition of a constant lightquantity of the light source 2.

Light beams reflected by the upper right parabolic cylinder curvedsurface 31a and directed slightly downward relative to the horizontaldirection, are again reflected by the upper second curved surface 33 andmade into substantially parallel light beams because the upper curvedsurface 33 is also made of a parabolic cylinder surface, as described indetail in the above-referenced Japanese Publication Nos. 61-63702 and61-71905. The lens 4 with a predetermined lens-cut as well known in theart gives a desired light distribution characteristic.

In this invention, the light shielding unit 35 is provided along thehorizontal line passing through the light source 2 in order for thelight beam from the light source 2 not to be directly applied to thesecond curved surface 33. As a result, stray light can be eliminatedcompletely. Further, the right third curved surface 35a formed on thelight shielding unit 35 at the position facing the light source 2 makeslight beams parallel and propagates them forward, in a similar manner aswith the second curved surface 33. The lens 4 therefore can provide adesired light distribution characteristic.

The upper fourth curved surface 37 also makes light beams parallel andpropagates them forward to thereby allow an adjustment of the lightdistribution characteristic.

Samples of the vehicle front lamp 1 and computer simulation made by thepresent inventor confirmed that the light flux capture ratio of thevehicle front lamp with an aperture area (170 width ×60 height) was157.7% of a conventional lamp with the same aperture area, thusimproving the luminance by about 60%.

FIG. 5 shows the main part of a second embodiment of a vehicle frontlamp according to the present invention. In this embodiment, the rightand left third curved surfaces 135a and 136a respectively formed at theright and left light shielding units 35 and 36 are slanted so as to thelight flux capture ratio, similar to the case of the upper rightparabolic cylinder curved surface 31a for example in the firstembodiment. The right and left third curved surfaces 135a and 136a areslanted inside toward the light source 2 by an angle of from 15 to 30degrees. The light distribution characteristic of the front lamp thusconstructed is shown in FIG. 6 wherein the function of the lens 4 is notincluded. The reflected light from the slanted right third curvedsurface 135a propagates toward the left to form a left spot CXXXVI,whereas the reflected light from the left third curved surface 136apropagates toward the right to form a right spot CXXXVI. These spots areformed of intersected parallel light beams reaching the positions on thehorizontal line H corresponding to the slanted angles. The arrangementof curved surfaces other than the right and left third curved surfaces135a and 136a is the same as that of the first embodiment, so that acentral spot C is formed at the intersection between the horizontal lineH and a vertical line V.

The advantageous effects of the second embodiment are as follows. First,the illuminance of the front lamp 1 is improved (refer to FIG. 4 for theoperation principle) because a light flux capture ratio is improved byslanting inside toward the light source the right and left third curvedsurfaces 135a and 136a. Second, the sagging phenomenon at opposite sideportions of the light distribution characteristic can be eliminated. Thesagging phenomenon occurs where the lens 4 is greatly slanted backwardas often seen with recent automobile design, and the parallel lightbeams directed only near the intersection of the horizontal and verticallines H and V are required to be diffused relatively broadly to thedegree sufficing produce a desired light distribution characteristic, byusing the lens-cut formed on the lens 4. According to this embodiment,the reflected light C at the central portion is diffused to the degreethat the central spot is made to be in contact with the right and leftspots CXXXVI and CXXXV, so that the light diffusion performed by thelens-cut is relatively narrow and the sagging phenomenon can beeliminated.

FIG. 7 shows the main part of the third embodiment of the vehicle frontlamp according to the present invention. In this embodiment, the rightand left third curved surfaces 235a and 236a formed on the right andleft light shielding units 35 and 36 are made of an ellipsoid ofrevolution having as a first focal point the light source 2. A convexlens 201 is mounted near the second focal point F2 of the right and leftthird curved surfaces 235a and 236a. A mash 202 is mounted near thefocal point F3 of the convex lens 201. A projecting type front lamp istherefore constructed of the right and left third curved surfaces 235aand 236a, convex lens 201 and mask 202. The light distributioncharacteristic CC of the third embodiment is shown in FIG. 8. Since themask 202 is made of opaque material so as to cover the unnecessaryportion of the light distribution, the shape of this mask 202 isprojected forward. As a result, for example, the light distributioncalled an European light distribution shown in FIG. 8 can be obtainedeasily, with the correct and sharp distribution along the horizontalline H. The arrangement of curved surfaces other than the right and leftlight shielding units 35 and 36 are the same as that of the firstembodiment, so a detailed description thereof is omitted.

FIG. 9 shows the main part of the fourth embodiment of the vehicle frontlamp according to the present invention. In this embodiment, the rightand left third curved surfaces formed on the right and left lightshielding units 35 and 36 are made of a composite parabolic cylindersurface having a plurality of parabolic cylinder surfaces which havefocal distances corresponding to the distance to the light source 2 andare disposed three dimensionally side by side along the inner surface ofthe right and left third curved surfaces without any step atintersections. Each parabolic cylinder surface is a portion of thesurface obtained by cutting a paraboloid of revolution in the verticaldirection at the width defined by two points on the curve obtained bycutting the paraboloid of revolution in the horizontal direction.

In operation of the fourth embodiment, the composite parabolic cylindersurface formed on the right and left light shielding units 35 and 36 atthe right and left sides of the light source 2, converges light beamsnarrowly in the vertical direction and reflects light beams broadly inthe horizontal direction. Therefore, by properly adjusting the focaldistance and width of each parabolic cylinder surface, a lightdistribution characteristic necessary for a vehicle front lamp can beobtained as desired. This arrangement dispenses with the lens-cut of thelens 4 to be formed at the positions corresponding to the right and leftthird curved surfaces 335a and 336a. The sagging phenomenon as describedwith the second embodiment can be avoided even if a lens 4 slantedgreatly backward is used. Also in this embodiment, the arrangement ofthe curved surfaces other than the right and left light shielding units35 and 36 is the same as with the first embodiment, so descriptionthereof therefor is omitted.

As described so far, according to the present invention, the firstcurved surfaces are slanted to improve the light flux capture ratio. Theupper and lower second curved surfaces are disposed in contact relationto each other. The right and left light shielding units 35 and 36 areprovided in order for the light beams from the light source not to beapplied directly to the second curved surfaces. Accordingly, thearrangement of the first and second curved surfaces allows an improvedlight flux capture ratio and hence a high illumination vehicle frontlamp, without causing stray light. The light flux capture ratio can thusbe increased by 60% over a conventional one. Further, there are providedthe third curved surfaces on the inside surface of the light shieldingunits facing the light source, to thereby reflect the light beams fromthe light source forward. By properly selecting the third curvedsurfaces, such as a paraboloid of revolution an, ellipsoid ofrevolution, and a composite parabolic cylinder surface, it becomespossible to realize a desired light distribution for variousapplications, such as for a slanted lens or the like.

While it is apparent that many modifications and variations may beimplemented without departing from the scope of the novel concept ofthis invention, it is intended by the appended claims to cover all suchmodifications and variations which fall within the true spirit and scopeof the invention.

I claim:
 1. A vehicle front lamp, comprising:a light source; an upperfirst curved surface made of composite curved surfaces for reflecting alight beam from said light source in the left direction of the vehicleand in the right direction of the vehicle, respectively, said upperfirst curved surface being mounted at a higher position than said lightsource; a lower first curved surface made of composite curved surfacesfor reflecting a light beam from said light source in the left directionof the vehicle and in the right direction of the vehicle, respectively,said lower first curved surface being mounted at a lower position thansaid light source; an upper second curved surface for reflecting a lightbeam reflected from said upper first curved surface for making saidlight beam reflected thereby substantially parallel in the forwarddirection of the vehicle, said upper second curved surface being formedat the right and left of said light source; a lower second curvedsurface for reflecting a light beam reflected from said lower firstcurved surface for making said light beam reflected therebysubstantially parallel in the forward direction of the vehicle, saidlower second curved surface being formed at the right and left of saidlight source; said composite curved surfaces of said upper first curvedsurface being slanted by an angle of 10 to 35 degrees so as to directsaid light beam reflected thereby downward; said composite curvedsurfaces of said lower first curved surface being slanted by an angle of10 to 35 degrees so as to direct said light beam reflected therebyupward; said upper second curved surface and said lower second curvedsurface being in contact relation with each other substantially along aline; and light shielding units mounted at the right and left of saidlight source along said line defining said contact between said upperand lower second curved surfaces.
 2. The vehicle front lamp of claim 1,further comprising a third curved surface provided at a surface of saidlight shielding units facing said light source, said third curvedsurface reflecting a light beam from said light source in the forwarddirection of the vehicle.
 3. The vehicle front lamp of claim 2, furthercomprising a fourth curved surface of a paraboloid of revolutionprovided at a central front side portion of each of said upper and lowerfirst curved surfaces, said central front side portions each defining alight unavailable area relative to said second curved surfaces.
 4. Thevehicle front lamp of claim 2, further comprising a further curvedsurface of a paraboloid of revolution provided at a central front sideportion of each of said upper and lower first curved surfaces, saidcentral front side portions each defining a light unavailable arearelative to said second curved surfaces.
 5. The vehicle front lamp ofclaim 2, wherein said third curved surface comprises a paraboloid ofrevolution.
 6. The vehicle front lamp of claim 3, wherein said thirdcurved surface comprises a paraboloid of revolution.
 7. The vehiclefront lamp of claim 2, wherein said third curved surface comprises aparaboloid of revolution, and is slanted by an angle of 15 to 30 degreesfor directing the light beam reflected thereby in a inward direction ofthe vehicle.
 8. The vehicle front lamp of claim 3, wherein said thirdcurved surface comprises a paraboloid of revolution, and is slanted byan angle of 15 to 30 degrees for directing the light beam reflectedthereby in a inward direction of the vehicle.
 9. The vehicle front lampof claim 2, wherein said third curved surface comprises a paraboloid ofrevolution.
 10. The vehicle front lamp of claim 2, wherein said thirdcurved surface comprises a composite ellipsoid.
 11. The vehicle frontlamp of claim 2, wherein said third curved surface comprises acombination of a plurality of parabolic cylinder surfaces.